Rotary actuator

The simplest actuator is purely mechanical, where linear motion in one direction gives rise to rotation.As their internal construction is generally similar (in principle, if not in size) they are often considered together as fluid power actuators.The differential pressure between the two sides of the vane gives rise to an unbalanced force and thus a torque on the output shaft.These used the manifold vacuum of a petrol engine to work a quarter-turn oscillating vane actuator.These can range from zero power actuators[notes 1] that are only used as display devices, such as air core gauges.
Electric rotary valve actuator controlling a butterfly valve
A variety of stepper motors
Radio control servo
Hydraulic or pneumatic rotary actuator, using a rack and pinion
valve actuatorbutterfly valveactuatorrotarytorquepneumaticallyhydraulicallyenergyspringselectric motorservomotorsstepper motorstorque motorStepper motorposition encoderRadio controlservomotorradio-controlled modelsmemory wirerack and pinionvacuumwindscreen wipersmanifold vacuumair core gaugesvalve actuatorspetrochemical industrySparkFun Electronics